Capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard
Technical field
The invention belongs to electrical equipment online supervision technical field, the present invention relates to more precisely the capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard for manual sampling in intelligent substation.
Background technology
Since 2010, the construction of intelligent substation progressively becomes the main flow of newly-built transformer station, and will attract the growth of explosion type in the future.In intelligent substation construction, emphasize by the on-line monitoring to primary equipment state, progressively realize the repair based on condition of component of primary equipment and the timely early warning of fault, accomplish few maintenance, non-maintaining, avoid the power outage and the casualties that due to equipment failure, cause.Capacitive power equipment occupies very large ratio in power transmission and transformation system, as bushing shell for transformer, lightning arrester etc., these power equipments are subject to the effect of the factors such as electricity, heat, rugged surroundings and occur agingly in operational process, and decreasing insulating, becomes accident potential.Dielectric loss is the important insulation index of reflection capacitive power equipment insulation status, and the stable operation of power equipment is had a very important role.The on-line monitoring of strengthening capacitive apparatus has huge society and economic benefit.
Capacitive apparatus medium loss measurement principle as shown in Figure 1.The voltage signal Un that dielectric loss measurement gathers bus PT is transformed to through voltage transformer (VT) the U2 signal that the ac voltage signal U1 of low-voltage-grade and the end shield current signal of measured capacitance type equipment Cx produce through high precision low current sensor (CT).U1 and U2 access modulate circuit and the AD sample circuit of dielectric loss measurement unit by cable, under the control of CPU, the signal acquiring system of U1 and U2 starts simultaneously, analog voltage signal to sensor output carries out synchronized sampling, then calculate capacitance type equipment end shield current signal Ix with respect to the phase differential Ph of busbar voltage Un, thereby obtain the parameters such as dielectric loss tan δ and capacitance Cx.The sampling precision of the synchronized sampling control technology of measuring unit, micro-electric current, frequency-tracking and the humorous rejecting that involves undesired signal are the keys that guarantees dielectric loss measurement precision.
Document one < < capacitive power equipment medium loss on-line monitoring method and device > > (Chinese Patent Application No. 200410026133.2) have disclosed a kind of method and apparatus of on-line monitoring capacitive power equipment medium loss.The method is by the voltage transformer (VT) signal of substation bus bar voltage and be arranged in high precision low current sensor signal on equipment ground line accesses Control Room computer PCI capture card by cable and calculate.There is following problem in the method: the one, do not carry out mains frequency tracking, and can not guarantee integer-period sampledly, there is fence effect and leakage effect, especially to phase place, bring larger error to the frequency spectrum calculating; The 2nd, voltage signal and end shield current signal fail to carry out site collection, but process by the computing machine that cable is moved Control Room to, due to mutual inductor output be weak signal, be unsuitable for the transmission of long distance, and be easily subject to the interference of outer signals; The 3rd, AD conversion chip adopts the resolution of 8 can not meet the feeble signal measuring accuracy requirement of leakage current; The 4th, do not meet the requirement of the digitized sampling of intelligent substation, the measurement of busbar voltage can not meet by merge cells samples, and is not suitable for the designing requirement of intelligent substation.
In intelligent substation; measurement for voltage and current signal; extensively adopt merge cells that signal is carried out to digitizing on the spot, by IEC61850-9-2 standard, take optical fiber and the crude sampling value of measurement is sent to the functional units such as measurement, protection, record ripple, dynamic vector as communication media.No longer adopt the mode of cable laying by simulating signal access measuring and protecting unit such as voltage, electric currents.In intelligent substation design, based on unified consideration, will can not gather voltage signal for the independent cable laying in dielectric loss measurement unit.And dielectric loss measurement unit needs the voltage signal of bus PT, this has brought problem to the application of traditional dielectric loss on-line measurement unit.The capacitive apparatus medium loss on-line monitoring unit based on IEC61850-9-2 standard of necessary new generation.
The capacitive apparatus medium loss factor on-line monitoring method > > (Automation of Electric Systems 2004 year October number 28th volume 19th phase 71st page) of document two < < based on DSP disclosed a kind of capacitive apparatus medium loss on-line monitoring method based on DSP.The method has considered to affect the factors such as signal interference, harmonic effects and mains frequency influence of fluctuations of measuring accuracy.But it is sampled as traditional analog quantity sampling, and the frequency tracking algorithm of its introduction is not suitable for the digitized sampling requirement based on IEC-61850-9-2 standard.
Document three < < have disclosed a kind of harmonic analysis method that adds Hanning window interpolation and can alleviate the impact of non-synchronous sampling on dielectric loss angular measurement based on adding the analysis > > (the 81st page of Automation of Electric Systems number the 30th the 2nd phase of volume in January, 2006) of the harmonic analysis method of Hanning window interpolation for Dielectric Loss Angle.First the method is not to be suitable for the intelligent substation based on digitized sampling based on analog acquisition equally.Secondly do not carry out frequency-tracking, the harmonic analysis method based on adding Hanning window interpolation of its introduction just alleviates the non-integer-period sampled impact on dielectric loss angular measurement, by frequency-tracking, does not realize integer-period sampled.
Summary of the invention
Goal of the invention of the present invention is:
1, in intelligent substation, gather bus PT voltage by merge cells in-site collecting, can not meet current dielectric loss measurement unit by the requirement of cable mode incoming analog signal, the present invention need solve the measurement of dielectric loss based on IEC61850-9-2 standard sample in intelligent substation;
2, gathering bus PT voltage is not same merge cells with the merge cells that gathers leakage current, and the synchronous acquisition that how to guarantee 2 road signals is the key of accurate measuring media loss;
3, the how DC shift in Inhibitory signal and 3 times, 5 times, the impact of 7 subharmonic on the measuring accuracy of dielectric loss angle of electrical network;
4,, in the situation that mains frequency fluctuates, how the dielectric loss measurement unit based on IEC61850-9-2 standard sample realizes frequency-tracking, prevents spectrum leakage and fence effect.
To achieve these goals, the present invention takes following technical scheme to realize:
A capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard, is characterized in that, comprises the following steps:
1) on capacitive apparatus ground wire, be socketed high precision zero flux leakage current transformer, the voltage signal of mutual inductor output is accessed to local mounted dielectric loss measurement unit, according to the AD sampling of minute pulse signal starting leakage current of B code output;
2) bus or circuit reference voltage are measured on the spot by merge cells, dielectric loss measurement unit accesses the reference voltage sampled value information of the IEC61850-9-2 standard of merge cells collection by optical fiber; Sampled value resampled and carries out Fourier transform, calculate amplitude, phase angle and frequency, adjusting resampling frequency, carrying out frequency-tracking;
3) according to step 1) the leakage current sampled signal that gathers carries out Fourier transform, calculates phase place and the amplitude of leakage current, integrating step 2) amplitude and the phase place of the reference voltage of the synchronization of calculating calculate dielectric loss value.
The aforesaid capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard, it is characterized in that: the algorithm resampling described step 2) is: establishing fs is merge cells sample frequency, Ts is the corresponding sampling period, fs ' is dielectric loss measurement unit resampling frequency, Ts ' is the corresponding resampling cycle,
T(n)=T(n-1)+Ts′
T (n) is interpolation point position, and floating number T (n-1) is last point interpolation point position, and establishing m is the maximum integer that is less than T (n), and establishes floating number u=T (n), and linear interpolation formula is as follows:
x′(n)=x(m)*(m+1-u)+x(m+1)*(u-m)
In formula, the n point that x ' (n) attaches most importance in sample sequence, x (m) is the m point value in former sample sequence, x (m+1) is the m+1 point value in former sample sequence.
The aforesaid capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard, is characterized in that: in described step 2) in, the step of frequency-tracking is as follows:
21) reference voltage signal Ux is carried out to the Fourier transform of complete cycle ripple;
22) Fourier transform result is carried out to filtering processing;
23) utilize the phase differential of the adjacent cycle of filtered first-harmonic vector calculation
24) utilize phase differential
calculated rate changes
25) calculate original signal frequency f=f
s-Δ f;
26) according to the up-to-date frequency values calculating, adjust resampling interval, return to step 21).
The aforesaid capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard, is characterized in that: the amplitude of the reference voltage of synchronization and phase place obtain be by internal clock time service unit, station by 2 road optical fiber B codes to time signal discontinuity surface when accessing respectively merge cells and dielectric loss measurement unit and realizing reference voltage and Leakage Current information same information acquisition.
The beneficial effect that the present invention reaches: in the present invention, disclosed the dielectric loss measurement method of a kind of basis based on digital signal samples, employing based on full station GPS to time B code to time realize synchronized sampling, utilize high precision zero flux leakage current transformer and high resolution A/D to guarantee sampling with high precision, utilize Fourier transform and frequency tracking algorithm to guarantee measuring accuracy.Adopt method of the present invention, can solve the capacitive apparatus dielectric loss measurement problem based on full station digitized sampling in current intelligent substation construction.And the gordian technique solutions such as a kind of synchronized sampling bringing due to digitized sampling, frequency-tracking have been proposed.In this scheme based on optical fiber B code to time time error is less than to 1 μ s, the measuring accuracy of frequency reaches 0.003Hz, meets the measurement requirement of dielectric loss completely.Use by the site collection to leakage current, high precision mutual inductor and high resolution A/D chip has guaranteed the precision and stability of measuring.More traditional metering system has been avoided because the long distance of small-signal transmits the signal attenuation bringing and is subject to the problems such as external disturbance.In addition, digital collection on the spot, is used optical fiber to replace cable, can save the cost of transformer substation construction, improves sharing of information, meets the theories such as economical environment-protective of intelligent substation.
Accompanying drawing explanation
Fig. 1 is traditional capacitive apparatus dielectric loss measurement schematic diagram;
Fig. 2 forms and structured flowchart by the capacitive apparatus medium loss measurement system based on IEC61850-9-2 standard of the invention process;
Fig. 3 is the core plate hardware structure diagram that explanation realizes dielectric loss measurement device of the present invention;
Fig. 4 is that explanation realizes the algorithm flow chart of measurement of dielectric loss of the present invention by program.
Embodiment
Capacitive apparatus medium loss on-line monitoring method based on IEC61850-9-2 standard, dielectric loss measurement unit is by gathering reference voltage signal with merge cells in IEC61850-9-2 standard traffic mode, by optical fiber B code to time realize the synchronous acquisition of reference voltage and leakage current, by high precision zero magnetic flux mutual inductor and 16 AD, realize the collection to leakage current, by resampling algorithm and software frequency tracking algorithm, realize the rejecting of undesired signal and integer-period sampled, the high precision on-line monitoring of realizing the loss of capacitive apparatus medium, comprises the following steps:
1) on equipment ground line, be socketed high precision zero flux leakage current transformer, the voltage signal of mutual inductor output is accessed to local mounted dielectric loss measurement unit (U1), for measuring the leakage current signal of capacitive apparatus, U1 have B code to time interface, utilize minute pulse signal starting AD sampling of B code output;
2) AC sampling of U1 (SV) interface (optical fiber port) is accessed to merge cells output interface or the corresponding AC sampling network (SV net) that gathers reference voltage by optical fiber, the sampled value information band of its collection has markers;
3) in U1 based on time scale information alignment leakage current signal and reference voltage signal, due to merge cells employing is at present the sample frequency of 80 points/cycle, need to resample, according to resampling data, carry out the signal processing methods such as spectrum analysis and obtain the parameters such as angular difference, leakage current, frequency, electric capacity, last according to the frequency adjustment resampling interval calculating, realize integer-period sampledly, improve measuring accuracy and stability.Specific algorithm is as follows:
31) raw data that is combined unit resamples:
If fs is merge cells sample frequency, Ts is the corresponding sampling period, and fs ' is dielectric loss measurement unit resampling frequency, and Ts ' is the corresponding resampling cycle,
T(n)=T(n-1)+Ts′
T (n) is interpolation point position, is generally floating number, and establishing m is the maximum integer that is less than T (n), and establishes floating number u=T (n), and linear interpolation formula is as follows:
x′(n)=x(m)*(m+1-u)+x(m+1)*(u-m)
32) resampling is carried out Fourier transform after finishing, and calculates amplitude and phase angle,
Fourier transform results can be expressed as:
In formula, the reference voltage of Ux for measuring, U
ofor its DC component, U
kmfor the amplitude of its each harmonic, α
kphase angle for each harmonic.I
xfor the Leakage Current of measuring, I
ofor its DC component, I
kmfor the amplitude of its each harmonic, β
kfor the phase angle of each harmonic, k is overtone order, and N is maximum overtone order, and t is the time, and ω is signal angular frequency.
Obtain voltage, current first harmonics phase angle α
1and β
1after, can obtain Dielectric loss angle:
tanδ=tan[90°-(β
1-α
1)]
33) carry out frequency-tracking, step is as follows:
331) reference voltage signal Ux is carried out to the Fourier transform of complete cycle ripple;
332) Fourier transform result is carried out to filtering processing;
333) utilize the phase differential of the adjacent cycle of filtered first-harmonic vector calculation
334) utilize
calculated rate changes
335) calculate original signal frequency f=f
s-Δ f;
4) according to the up-to-date frequency values calculating, adjust resampling interval, return to step 1).
Be a preferred embodiment of the present invention below, comprised a concrete dielectric loss measurement unit based on 61850-9-2 standard that adopts method of the present invention to realize.Other feature, object and advantage of the present invention also can be found out from the explanation of embodiment and accompanying drawing.
From accompanying drawing 2, can see, capacitive apparatus medium loss measurement system has comprised mutual inductor, clock unit, merge cells, dielectric loss measurement unit, comprehensive monitoring unit or station end monitoring means.Clock unit by wireless time benchmark or wired time reference signal receive to time information.By the optical fiber B code producing to time signal by optical fiber transmission to merge cells, dielectric loss measurement unit and other need to time device.Merge cells is arranged in outdoor cabinet on the spot, is converted on the spot digital signal gives dielectric loss measurement unit and measuring and protecting device with reference to voltage signal.Dielectric loss measurement unit accept B code to time signal, gather leakage current signal and complete with reference voltage signal synchronize with the calculating of dielectric loss amount etc.Station level monitoring system or comprehensive monitoring unit will be given in dielectric loss unit in result of calculation and data.
Accompanying drawing 3 is hardware structure figure of dielectric loss measuring set core plate.In figure, high-performance embedded processor P owerPC is responsible for 2 road serial line interfaces, and wherein 1 tunnel is RS232 debug port, and an other road is the station level system communication interface for adopting RS485 to communicate by letter.Fiber optic Ethernet communication port 1 is for communicating interface with the main intelligent electronic device of intelligent transformer assembly or station level analytic system.Fiber optic Ethernet communication port 2 is for the IEC61850-9-2 standard traffic with merge cells.PowerPC processor also complete simultaneously dielectric loss algorithm calculating and with outside signal procedure.FPGA implement device to time system and AD signal synchronized sampling.Outside FLASH is for the storage of program.
Accompanying drawing 4 is process flow diagrams of application program in the flush bonding processor of dielectric loss measurement unit.In process flow diagram, be divided into vectorial angle, amplitude and frequency computation part module that one of two module are reference voltages.Another module is phase angle, amplitude and the dielectric loss computing module of leakage current.
1. dielectric loss measurement unit in first module and merge cells communicator program deposit the reference voltage of the IEC61850-9-2 standard receiving in buffer area, to buffer area IEC61850-9-2 data resolve extract whole time original sampling data 2., to original, carry out resampling value 3. and counterweight sampled data is carried out spectrum analysis and filtering, calculate the amplitude of first-harmonic vector of whole time and phase angle 4..According to the phase angle information of a upper cycle, calculate phase angle difference, according to phase angle difference, calculate the difference of current calculated rate and actual frequency, according to the current calculated rate of frequency difference correction 5..According to current calculated rate, adjust the resampling frequency of voltage signal and the sampling period of leakage current 6..
Second module according to sample frequency that in module one, 6. step calculates and B code to time information in whole time, start leakage current sampling 7..Sampled data is carried out to Fourier transform, calculate the amplitude of first-harmonic vector and phase angle 8..Wait for the 4. result of calculation of step, obtain the phase information of synchronization reference voltage, calculate dielectric loss.
The present invention is illustrated according to the preferred embodiment, should be appreciated that but above-described embodiment does not limit the present invention in any form, and all employings are equal to replaces or technical scheme that the form of equivalent transformation obtains, within all dropping on protection scope of the present invention.